Stereoscopic endoscope

Abstract

In an objective optical system of a stereoscopic endoscope, a pair of positive lenses are disposed downstream a pair of negative lenses for the right and left eyes at the leading end of the scope so as to respectively correspond thereto, whereby aberrations generated by the pair of negative lenses are corrected favorably. Successively from the object side, a negative lens pair 1, a positive lens pair 2, and a positive lens group 3 are disposed, whereby an incident luminous flux from the object side is caused to form an image on an imaging surface 6 of a CCD. The image-surface-side planar surfaces of the lenses L 2 in the second lens pair 2 are respectively formed with stops 5 which are attached thereto or deposited thereon. Each of the lenses L 1 constituting the first lens pair 1 and its corresponding lens L 2 constituting the second lens pair 2, with the stop 5, are integrated together in a concentric state; and thus formed pair of members are disposed in parallel for the right and left eyes, while being made movable symmetrically to each other in directions (arrowed A directions) with respect to the optical axis of the positive lens group 3.

What is claimed is: 
     
       1. A stereoscopic endoscope comprising: an elongated inserting portion;   an objective optical system disposed within a tip of said inserting portion; and   imaging means, disposed within said inserting portion, for capturing an object image formed by said objective optical system;   wherein said objective optical system comprises, successively from the object side, a first lens pair made of a pair of negative lenses disposed in parallel to each other, a second lens pair made of a pair of positive lenses disposed in parallel so as to respectively correspond to the lenses of said first lens pair, and a positive lens group; and   wherein said pair of positive lenses constituting said second lens pair are movable symmetrically to each other in directions perpendicular to an optical axis of said positive lens group.   
     
     
       2. A stereoscopic endoscope according to claim 1, wherein a stop or light-shielding plate is disposed between said second lens pair and said positive lens group; and wherein each lens constituting said first lens pair, and each lens constituting said second lens pair are integrally formed as a half of a pair of upper and lower members disposed in parallel. 
     
     
       3. A stereoscopic endoscope according to claim 1 wherein said positive lens group comprises two or more lenses and wherein said positive lens group is a net positive group. 
     
     
       4. A stereoscopic endoscope comprising: an elongated inserting portion;   an objective optical system disposed within a tip of said inserting portion; and   imaging means, disposed within said inserting portion, for capturing an object image formed by said objective optical system;   wherein said objective optical system comprises, successively from the object side, a first lens pair made of a pair of negative lenses disposed in parallel to each other, a second lens pair made of a pair of positive lenses disposed in parallel to each other concentrically with their respective lenses of said first lens pair, and a positive lens group; and   wherein said pair of positive lenses constituting said second lens pair are movable symmetrically to each other in directions perpendicular to an optical axis of said positive lens group.   
     
     
       5. A stereoscopic endoscope according to claim 4, wherein a stop or light-shielding plate is disposed between said second lens pair and said positive lens group; and wherein said stop or light-shielding plate, each lens constituting said first lens pair, and each lens constituting said second lens pair are integrally formed as a half of a pair of upper and lower members disposed in parallel. 
     
     
       6. A stereoscopic endoscope according to claim 4 wherein said positive lens group comprises two or more lenses and wherein said positive lens group is a net positive group.